Cementless base for incandescent lamps



June 7, 1938, M. EQMOGOWAN 2,119,681

CEMENTLESS BASE FOR INCANDESCENT LAMPS Filed Dec. 21, 1935 2 Sheets-Shet l v ATTORN June 7, 1938. M. E. MQGOWAN 2,119,681

CEMENTLESS BASE FOR INCANDESCENT LAMPS Filed 1150. 2-1, 1935 2 Sheets-Sheet 2 J z? 2 w I wi I g 2a Patented June 7, 1 938 Michael E. McGowan, Bloomfield, N. 1., assignor, by mesne assignments, to Westinghouse Electric and Manufacturing Company,

East

Pittsburgh, Pa., a corporation of Pennsylvania Application December 21, 1935, Serial No. 55,520

5 Claims.

This invention relates to the manufacture of electrical devices such as inca'ndenscent electric lamps in which a base is secured to a lamp'blllb and more particularly to a bulb and base so constructed as to permit the base to be secured to the bulb by mechanical means.

In the manufacture of electrical devices, such for example as incandescent electric lamps, it is the practice to provide the lamp with a base in the form of a threaded metallic shell or cap having one end open to receive the end or neck portion of a glass bulb. Bases of the above character' are usually secured to the bulb by means of a quantity of cement which is deposited in the base, after which the bulb and base are disposed in the desired relation and the cement is subjected to a baking operation to harden and firmly secure the bulb and base in fixed relation.

The above constructionha's been extensively used but certain disadvantages attend this mode of manufacture since it is time consuming, relatively expensive, and involves a heat-treating operation.

Heretof'ore many attempts have been made to provide a mechanically secured base but owing to the difficulty in providing a lamp bulb of such construction as to include the necessary elements for cooperating with means on the base, it has been diflicult, if not impractical, to furnish a suitable mechanically secured base. This is especially true when applied to lamps of the popular standard types in which case the base must be exactly similar to a standard base which is secured to. the bulb by cement.

A mechanically attached base must be secured against endwise removal; it must be held against .rotary or lateral movement; and must have a tight and preferably a water-sealed fit against the bulb.

Heretofore when making a mechanical base the bulb neck was formed with indentations or with specially formed surfaces to receive collars over which the base was forced and held against removal. In spite of the various means employed to hold'the base in place, it has been impossible to provide a mechanically secured base without some play or looseness, in so far as I am aware. This wasdue to the fact that when shaping the bulb neck to receive a base the base lacked the necessary seating surface on the bulb owing to the long established practice in glass working.

which taught that only rounded corners were practical when making a bulb. It was believed that any sharp corners would result in internal stress, resulting in cracks causing leaks sincethe bulb is evacuated to a relatively high degree.

In my co-pending application Serial No. 55,519 filed December 21, 1935, entitled Method of sealing-in and molding lamp bulbs and assigned to the present assignee, a method is shown and described wherein a bulb neck is formed with an annular shoulder which provides a surface in a plane substantially transverse to the longitudinal axis of the bulb.

In accordance with the present invention I take advantage of the discovery that the bulb neck may be formed with an angular shoulder, and utilize the shoulder to seat the upper edge of a base. This gives the base a fixed position with respect to the bulb and in conjunction therewith I provide means for locking the base with its upper edge against the shoulder, and for securing the base against relative rotary movement.

It is, therefore, an object of the present invention to provide a simple and efiectlve mechanicallysecured base.

Another object" of the invention is to provide a mechanically secured base in the form of the standard threaded shell free'from rotary or lateral movement relative to the bulb neck.

A- further object of the invention is to provide a lamp bulb with the neck portion so formed as to cooperate with mechanical means for securing I a base to. the bulb neck.

A still further object of the invention-is to provide a lamp bulb having what may be termed a straight shoulder (as distingfiuishedfrom a Fig. 1 is a side elevational view of -a bulb with" a base attached in accordance with the present invention; l

, Fig. 2 is an enlarged detail view of the base and bulb neck shown in vertical cross section;-

Fig. 3 is a view similar to Fig. 2, but shows a section taken through the base at another point to show locking means;

Fig. 4 is a view of the lower end of the bulb neck showing depressions and slot to receive holding members;

Fig. 5 is a view taken on line V-V in Fig. 4;

Fig. 6.is a view of a base partly broken away to show holding means extending from the inner wall of the base;

Fig. 7 is a view, taken on line VII-VII in Fig. 6;

- Fig. 8 is a side elevational view of a bulb with a base constructed in accordance with the present invention, but showing a modified form of the securing or holding means;

Fig. 9 is an enlarged detail view of the base and the lower end of the bulb shown in Fig. 8, partly in vertical cross section;

Fig. 10 is a detail view of the lower end of the bulb neck shaped to receive the modified holding means;

Fig. 11 is a view taken on line XI-Xl in Fig.

.Fig. 12 showsthe base with holding means to securethe base to the bulb neck shown in Fig. 10; and

Fig. 13 is a view taken Fig. 12.

Although the present invention may be employed to mechanically secure a base to any type of lamp bulb or similar device, it is shown and described as applied to an incandescent lamp bulb in having a neck portion Ii and the usual stem l2 with an arbor 13 to support a filament l4. The filament is provided with conductors l4 and i5 which are sealed. in a press l1 and extend through the stem tube l2 and terminate in the form of 1m line xm-xrn in .fiexible lead wires l8 and I9. The-bulb may b provided with the usual exhaust tub'e 2|.

In accordance with the present invention the bulb neck is formed with an annular shoulder 22 which provides a fiat surface 22' disposed in a plane substantially transverse to the longitudinal axis of the bulb. This surface provides a seat for the upper edge 20 of a base 23. The base may bev of the usual screw thread type for standard sockets. As shown, the base comprises a tubular metallic shell 24 closed at one end by an insulative web 25 of glass which carries a bottom contact member 26. The lead wire l9 may bev electrically connected to the contact 26 and lead l8 may be electrically connected to the shell 24.

The bulb neck in addition to having the fiat shoulder is formed to provide a cylindrical plug or extension 21 of a diameter so proportioned that the plug firmly fits the inside surface of the shell 24. It will be noted that the base shown is of the screw threaded type and that the upper end of the base is in the form of a collar 26' and that the plug 21 is provided with an annular surface 21' which fits the collar. The lower end 28' of the plug 21 is of a reduced diameter to fit the inner surface 30' of the threads. Thus the base when fitted over the plug is held in alignment with the longitudinal axis of the bulb by reason of its contact with the plug.

Around the annular surface 21' of the plug are, in the present embodiment,.provided generally triangular indentations 23 and generally rectangular slots 29. The indentations receive lips 39 which in' the present embodiment are generally triangular and may be formed, and extended inwardly, from the wall of the shell, and the slots 29 receive bosses or wards 32 which may be formed from the shell to correspond with the receiving slots 29 and extended inwardly. The lips and the wards may be so formed as to be resilient or spring-like.

When a base is to be applied to a bulb-neck, the base is adjusted until the wards slide into the slots and as the base is forced over the end of the bulb neck to bring the edge 29 thereof into contact with the shoulder 22, the lips enterv the indentations 28 and lock the base against endwise movement. The wards 32 in the slots 29 hold the base against relative rotary movement.

Although the lips may be positioned to snap into the indentations when the base is in place, it has been found practical to leave the lips fiush with the wall of the base and after the base has been positioned the lips may be bent inwardly and firmly pressed into the indented surface of the bulb neck. These indentations may be formed to almost exactly fit the lips so that when the lips are pressed into their locking positions they occupy the entire space provided by the indentations and thus firmly hold the base against any relative rotary movement. It will be understood that the. slots 29 serve to align the base so that the lips will register with the indentations.

It will be noted that lips hold the edge- 20 tightly against theshoulder surface 22' and it has been found that by making the plug portion 21 of the bulb neck a tight fit and by reason of the firm contact between the upper edge of the base and the shoulder, the base is sealed to the extent that moisture is prevented from reaching the lower inside,portion of the base. It has been found, if the plug portion of the neck is dipped in a solution of a lacquer just before the base is applied, that an exceptionally effective -'seal is provided.

The present construction, however, makes it possible to bring the shell and bulb neck into such intimate relation that a sealis-eiiected for all practical purposes. though the lips are shown of angular form, that any shape of lip or securing projection will answer the purpose. For example, the indentations may be in the form of circular recesses and after the base is in position on the bulb neck the material of the base, which is usually soft brass, may be forced into the recesses.

This may be done by piercing the metal and forcing in a lip, or the metalmay be forced into the recess without breaking the wall of the shell. The ward may also be formed from theshell without breaking theshellwall;

Figs. 8 to 13 show a base having oppositely directed lips 33 and 34 to enter depressions 35 and 38 respectively, on the bulb neck. In this case the base is applied to the bulb neck and adiusted until the lips snap into the depressions. The lips 33 lock the base against endwise movement and the lips 34 hold it "against relative rotary movement. In this instance the depressions 35 and 36 are all generally rectangular, the first set elongated parallel to the axis of the bulb neck and the other circumferentially.

The present invention provides a simple form of mechanically secured base and, as will be noted, the bulb and base cooperate to make the mechanical attachment possible. It is vitally important in a device of this kind to be able to prevent lost motion and particularly a lateral or sidewise movement of the base relative to the bulb neck. The difliculty has been in holding the metallic shell against movement relative to the bulb neck. This has been a perplexing problem for many years.

The advantages of a mechanically attached base were well recognized and many attempts were made to produce a mechanically secured base to meet practical requirements. The bulb neck, however, presented a hard smooth surface which, owing to the character of the material. could not be gripped too tightly without cracking, making it dimcult to effectively secure a base without,

some means of holding the base against sidewise movement. Heretofore when the bulb neck was provided with a rounded shoulder the upper edge It will be understood, al-

2,11e,ca1

' seat which extends transverse to the axis of the base and it is only necessary to provide holding means to prevent removal of the base and hold it .in contact with the abutment which resists movement of the base equally at all points around its edge. By reason of the annular abutment the bulb neck may, as shown, be of cylindrical form to snugly fit the base so that when the base is slid over the bulb, neck and against the abutment,

it is held in the absence of play and the wards, lips and other deformations that may be made, merely serve to lock the base in place, keeping it against the abutment and preventing relative ro-' tary movement.

A base constructed in accordance withthe present invention is easily applied and of relatively low cost, and in practice it has been found to hold as well as when applied by the more laborious and costly operation of cementing, if not better.

Although a preferred embodiment ofthe invention is shown and described herein, it is to be understood that modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed:

1. An electrical device comprising a bulb having a neck terminating in a generally cylindrical reduced end portion forming a flat annular shoulder with said neck, a slot indented in the outer surface of said end portion and extending generally parallel to the axis of said bulb, another indented slot, spaced from said first mentioned slot and extending circumferentially with respect to saidend portion, and a tubular metallic screwthreaded base closely fitting the reduced end portion of said neck, said base having a plain portion with a portion struck therefrom and fitting in said first mentioned slot to prevent relative rotation between said base and bulb, and another portion struck inward therefrom and fitting in said circumferentially extending slot to prevent relative axial movement between said base and bulb, the edge of said base engaging said shoulder, and the outer end of said reduced portion being restricted sufficiently to fit the inner surface of the threads on said base.

2. An electrical device comprising a bulb having a neck terminating in a generally cylindria portion struck therefrom and fitting in said first mentioned slot to prevent relative rotation between said base and bulb, and another portion struck inward therefrom and fitting in said circumferentially extending slot to prevent relative axial movement between said base and bulb, and the edge of said base engaging said shoulder.

3. An electrical device comprising a bulb having va neck terminating in a generally cylindrical reduced portion stepped to provide a generally cylindrical further reduced end portion, aslot indented in the outer surface of said reduced portion and extending generally parallel to the axis of said bulb, another indented slot, spaced from said first mentioned slot and extending circumferentially with'respect to said end portion, and a tubular metallic screw-threaded base closely fitting the reduced portion of said neck, said base having a plain portion with a portion struck therefrom and fitting in said first mentioned slot to prevent relative rotation between said base and bulb, and another portion struck inward therefrom and fitting in said circumferentially ex-' posed between said slots around the periphery of said reduced portion, and a tubular metallic screw-threaded base closely fitting over the reduced portion of said neck, said base having a plain portion withwards struck therefrom and each fitting in one of said slots to prevent relative rotation between said base and bulb, and lips struck inward from said plain portion and fitting said triangular indentations to prevent relative axial movement between \said base and bulb.

5. An electrical device comprising a bulb having a neck terminating in a generally cylindrical reduced portion stepped to provide a generally cylindrical further vreduced end portion, a plurality of rectangular slots indented in the outer surface of said reduced portion and extending generally parallel to theaxis of said bulb, other generally rectangular slots indented in the outer surface of said reduced portion, disposed between said first mentioned slots, and extending circumferentially around said end portion, and a tubular metallic screw-threaded base fitting over the reduced portion of said neck, said base having a plain portion with wards struck therefrom and fitting said first mentioned slots to prevent relative rotation between said base and bulb, and

other wards extending approximately at right angles to said first mentioned wards and fitting in said circumferentially extending slots to prevent relative axial movement between said base and bulb.

' MICHAEL E. MCGOWAN. 

